The present invention relates to circuit interrupters and housings therefor, and more particularly to an improved housing structure.
Circuit interrupters, particularly those rated at higher voltage and current levels, are frequently enclosed in metal cabinets or housings which may be disposed either within a building or out-of-doors. Frequently such housings are fabricated of sheet metal pieces, which are bolted together to form the desired structure. Ordinarily such structures are reinforced with angle or channel bracing. At least a portion of the structure is conventionally reinforced to withstand the stresses and reaction forces of the operating mechanisms which open and close the circuit interrupters.
As is well known by those skilled in the art, the circuit interrupters for industrial circuit breakers are large and relatively massive. In order to cause them to open and/or close with the necessary speed, large and powerful operator mechanisms are required. Frequently such mechanisms take the form of spring-loaded mechanical movements, often provided with electric motors and gear trains or rachet units for charging opening and closing springs. Electric signals are utilized to operate tripping mechanisms such as switches and solenoids which release the energy stored in the springs to open or close the interrupter mechanisms.
Owing to the size and weight of the interrupters and associated apparatus, and to the large forces required to move them rapidly, the structures which carry the operating mechanisms and the circuit interrupters must be extremely strong and must resist movement during operation of the system. For this reason, it has been conventional to construct such units by building a substantial subframe from angle, channel or similar structural material and to mount the various operating mechanisms, linkages, etc. to the rigid subframe. Sheet metal panels, or partly-assembled sheet metal cabinets, are then attached to enclose the structural framework. Supporting members or legs are frequently fabricated separately and then bolted or welded to the heavy subframe. To complicate matters further, it is ordinarily necessary to operate three circuit interrupters in synchronism. This is frequently accomplished with a common linkage or shaft which extends within the housing. The linkage must be rigidly supported to maintain alignment and to prevent deflection when the mechanism operator is actuated.
While such structures have the advantage of being relatively simple to design and fabricate, they are relatively heavy and require the use of costly structural material. Accordingly, it will be appreciated that it would be highly desirable to provide an enclosure for a circuit interrupting mechanism which is sufficiently rigid but is lighter, and uses less structural material, than those heretofore known.
It is accordingly an object of the present invention to provide an improved circuit interrupter housing.
It is another object of the invention to provide a circuit interrupter housing which localizes stresses and eliminates the need for heavy structural subframes.
Another object of the invention is to provide a circuit interrupter housing with a lightweight, adjustable leg mounting.